Underreamer



Jan. 3, 1928. 1,655,108

C. E. REED UNDERREAMER Filed Dec. 5. 1925 Patented Jan. 3, 1928.

PATENT OFFICE.

CLARENCE EDW. REED, OF WICHITA, KANSAS.

UNDERREAMER.

Application filed December My invention relates to underreamers for use in drilling wells for the purpose of enlargin a hole drilled below casing and has for its object to provide a construction of underreamer which will be particularly adapted for use in wells of small diameter. Several forms or" underreamers are known to the trade and in satisfactory use in wells of diameter from ten inches upwards and some of them are used in wells of diameters as low as six inches but in the smaller diameters effective work done by the reamers is attended with extreme risk of the loss of the tools in the wells from breakage of the reaming bits or cutters, which necessarily have to be of very small size.

In all types of underreamers with which I am familiar, it has been impossible to produce cutters of the small sizes required which can be depended upon to have the strength necessary to stand up under the conditions to which they are subjected in the operation 'of underreaming. Very deep wells are of recent development and have made necessary the useof easing of increased thickness to withstand the heavy pressure at greater depths. The practice of increasing the thickness of the casing and retaining the previous outside diameter has necessarily reduced the interior diameter of the casing through which the drill must pass and increases the difference in diameter between the hole drilled below the casing and the diameter to which the hole must beenlarged by the underreamer to permit the casing to be lowered. The increased amount of Work thus required to be done by the underreamer is not particularly difficult in sizes above eight inches in diameter but in underreamers for wells of smaller diameter increases dii'iiculties which were already so great that they could notbe and the always present 'semet satisfactorily rious diliiculty in the operation of any underreamer with which been breakage and loss of cutters, necessitating fishing jobs which are expensive and have oftentimes resulted in the loss of the well.

The present invention is designed and provides an underreamer in which the cutters are thickened in the section that usually breaks, and the cutters are formed to surround the lower end of the underreamer body, wh ch cutters w provides a. solid backing for the hen in operating position. This a I g n I I A on vs a uniform distributionof I am familiar has.

3, 1925. Serial NO. 72,906.

derreamer body, thereby developing the ulti mate strength of the metal by eliminating weak points or sections, and the construction is such that the cutters can move only upward and downward. This design permits almost any desired distance of movement longitudinally of the reamer body in the movement of the cutters from collapsed to expanded position.

My invention provides a form of cutter which has large bearing surface to carry all loads and thrusts regardless of the direction from which the thrusts are imposed on the body.

Another object of the invention is to provide reaming bits or cutters comprising a solid body only of novel form eliminating all wings, shanks or other extending portions of thin section upon which other types of underreamer cutters must depend to hold the cutter against outward movement or movement in any direction, except downwardly. In this invention no operating thrusts at any time are taken by the means for drawing the cutters against its bearing and abutment on the underreamer body.

-With the objects above indicated, and other objects hereinafter explained, my invention consists in the construction and combination of elements hereinafter described and claimed:

Referring to the drawings:

Fig. 1 is a side view of the lower portion of an underreamer embodying my invention, the underreamer cutters being in operating position and the cutter on the right side being shown in section.

Fig. 2 is a plan view looking upward at the bottom of the underreamer as shown in Fig. 1.

Fig. 3 is a sectional viewthrough Fig. 1 on the line A A.

Fig. 4 is a side view ofan vunderream'er embodying my invention, the underreamer being shown in position inserted in the well casing, the reaming bits or cutters being shown in collapsed position, and of slightly different form at their lower inner sides.

In the drawings, 1 indicates the underreainer body which is bored in its upper portion and screw threaded at the upper end. Within the bore of the body is mounted a coil spring 2 which surrounds a rod 3 which carries pin 5. The coil spring 2 bears at its upper end against the danger. lead 2* ot the rod and bears at its .1; r end lowered through the casing.

, 1 wn' snown 1n r 1g.

against the shoulder 1 of the body 1. The spring 2 tends to force the rod upward in the body. The pin 5 ismounted in the lower end of the rod 3 and pivotally supports the hangers 7.

In order to permit the cutters to pass through the well casing, the cutters are drawn downward to the collapsed position at, thus drawing the pin 5 and rod 3 down against the resistance of the spring 2.

Initial collapsing of the tool to the position shown in a may be done by manual operation in any suitable way. Usually a hook arrangement is placed over each cutter and as the toolhangs from the derrick or some other support, a block and tackle for instance may be used to collapse it. Y

The underreamer body 1 is centrally bored from its upper end. to a point in line with the abutm-cnts 6. In line with the lower portion of the central. bore 1 is formed a slot 15 extending laterally through the underreamer body and in which the pin 5 rides. In expanded position the pin 5 is at the upper end of the slot 15 and in collapsed (Fig. l) position it is at the lower end.

To hold the cutters in collapsed position a-pin leis passed through a hole 4; in the rod "3 and by its engagement with the upper end of the slot 15 prevents the rod from being drawn up by the spring. have been inserted within the casing the pin 4: is withdrawn and the underreamer may be For a detail disclosure of the expanded position and collapsed position see patent of Swan No. 1,507,444, Sept. 2, 1924, Figs. 5 and 3 respectively. The head of the rod 3 and the pin a limit and control the movement of the spring. The pin 5 is the means for attaching the hangers 7 to the rod 3, the hangers 7 being pivoted to the pin 5. The lower ends of the hangers 7 are threaded to receive a nut. There are two hangers 7 for each cutter. The lower end of the hanger 7 passes through a vertical hole 130i which there are two in each cutter and screw threads into a nut 8 which prevents the cutter slipping off the end of the hanger 7. The hole 13 in the cutter may bechanged to a form other than round and an upset end could be used on the hanger 7 instead of a nut 8. The underreamer body is formed with abutments 6. Two cutters are shown in the but three or more may be used in larger sizes. The lower portion of the underreamer body 1 is formed of an outline which, for want of a more accurate name, may be described, as seen in cross section, as two bulbs 11 whose stems connect to form a web'lO. In Fig. 3 two cutters 9 are shown surrounding the bulb portions 11 of the untially their When the cutters treme outer and lower derreamersbody. The only way the cutters can be assembled on the underreamer body is by pushing them upwardly over the lower end of the bulb shaped ribs. The portion of the cutters designated by 12 surround the bulb portion of the underreamer body for half or more the length of the cutter and in large sizes the full length of the cutter as shown in Fig. t. Adjacent to the abutments Gthe bulb and web shaped portion or" the underreamer body is wider than at the end of the body, thereby forming a wedge which expands the cutters as they move upward longitudinally of the underreamer body to .the operating position against the abutments 6. [is clearly shown inthe drawings, the shape or? the cutters makes impossible any movement of the cutters except longitudinally of the body. Any desired length oi longitudinal movement 0 the cutters may be readily obtained by changing the angle of the wedge. Tt will be noted that the cutters are thic test where the load falls. The cutters bear substanentire length around the bulb shaped portion of the underreamer body and particularly the upper half of the cutter, which is the section that usually breaks in other types of cutters.

It is of course well known that underreamers of this type are of the reciprocating cable tool system of drilling wells by percussion, the underreamer cutters striking a blow. The blow is concentrated on the exedge of the cutter. These underreamers operate at the sides of a well enlarging a hole already drilled and in the nature of things it is impossible to expect or to obtain a uniform point of contact or direction of thrusts from the blow and the pounding under these conditions frequently breaks underreamer cutters, particularly the portion of the cutter used to fasten or hold it in the underreamer body. 7

My invention provides a form of underreamer cutter which does not operate in aslot or other recess within a body, necessitating thin portions of the cutters for retaining means and which at times and in fact often are subjected to violent thrusts from impact, but my invention provides a form of cutter which is new and combined with the shape of the underreamer body supporting it gives the maximum strength of the metal used and a thrust from any direction is supported by the solid metal of the underreamer body.

As the method of inserting the underreamer in the casing by collapsing the cutters on the derrick floor and thus inserting them within the casing and also the use of a spring to draw the cutters upward against the abutment, is well known in the art, no detail description has been thought necessary in this specification.

, adapted Having thus described my invention, what I claim is:

1. In combination in an underreamer, a body having a downwardly tapered extension, said body extension comprising a web having ribs defining its tapering edges and presenting in cross section a pair of bulbshaped enlargements connected by a relatively narrow web, a pair of oppositely disposed cutters having longitudinal undercut recesses to receive said ribs and to be retained thereby upon said bony, the mouths of said recesses being in width substantially no greater than the thickness of the web of the body, said body having an axial bore therein, a spring actuated axially movable rod in said bore, supporting han ers tor said cutters, pivotally connected to said rod, each cutter being orovided at its upper end with a pair of hanger receiving holes disposed on opposite sides of its rib receiving recess, said holes extending downwardly through said cutters and terminating in notches cut on the inner walls or" said cutters, said hangers being adapted to be inserted in said holes and means engaging the ends of said hangers through said notches to secure the hangers to the cutters.

2. In combination in an underreamer, a body having a downwardly tapered extension, said body extension comprising a web having ribs defining its tapering edges and presenting in cross section a pair of bulbshaped enlargements connected by a relatively narrow web, a pair of oppositely disposed cutters having longitudinal undercut recesses adapted to receive said ribs and to be retained thereby upon said body, the mouths of said recesses being in width sul si'antially no greater than the thickness of the web ot' the body, said body having an axial bor, therein, a spring actuated axi ally movable rod in said bore, supporting hangers for said cutters pivotally connected to said rod, each cutter being provided its upper end with a pair of hanger receiving holes disposed on opposite sides of its rib receiving recess, said hangers being adapted to be inserted and secured in said holes to secure the hangers to the cutters.

In testimony whereof, I atfiX my signature.

CLARENCE EDW. REED. 

